溫度對台灣土雞公雞之精液性狀與精子熱緊迫蛋白質70之影響

Abstract

本省地處亞熱帶，夏季高溫多濕，常使畜禽受到熱緊迫之影響造成繁殖性能低下。已知細胞或生物體對熱或其他緊迫之適應反應特徵為被誘發合成熱緊迫蛋白質(heat shock proteins; HSPs)，因此本試驗嚐試研究溫度對公雞之精液性狀與精子HSP70之影響，以期能對熱緊迫蛋白質與精子性狀的關係有多一點的瞭解。試驗一將試驗雞隻分成對照與加熱兩組，對照組置於25℃；加熱組在37℃與80%R.H.緊迫環境處理4小時。試驗期間分為適應期2週、緊迫期6週及恢復期4週，觀察其精液性狀的反應。試驗二將公雞精液以Phosphate Buffered Saline (PBS)或Beltsville Poultry Semen Extender (BPSE)稀釋分別置於4℃、25℃、35℃和41℃恆溫水浴槽內加熱並於2、4、6及8小時分析精液性狀與精子HSP70濃度。 試驗一之公雞在12週試驗期間內均有相當好精液量與精子濃度，熱緊迫處理反而造成處理組的精液量顯著地高於對照組。緊迫期與恢復期的精子濃度與精子活力均較適應期低，精子HSP70濃度也顯著上升。於緊迫期間，直腸溫與血液pH值之間有正相關(對照組與處理組分別為0.29與0.27) (P<0.05)。而處理組之直腸溫與血液pH值及精液量有正相關(分別為0.21及0.31) (P<0.05)，而處理組之直腸溫、血液pH值及精液量亦與精子活力有負相關(分別為-0.27、-0.23及-0.28) (P<0.05)。表示有些雞隻無法適應熱緊迫而使直腸溫與血液pH值上升，因為飲水增加而有較高之精液總量，而這高體溫也可能對精子活力有影響。試驗二之精子活力及死亡率在較高溫度時(35或41℃)會隨著時間有顯著地變差，尤其是以PBS稀釋者更為明顯。置於41℃的處理有較多之畸形精子，放置8小時觀察到之畸形精子以腫脹者為多。觀察精子HSP70之濃度在8小時期間的變化，發現以BPSE稀釋的精子，或是以PBS稀釋之精子在25℃溫度下，其HSP70濃度變化很小。而以PBS稀釋精液在35℃及41℃下HSP70濃度則迅速的下降。以PBS稀釋的精子，其HSP70濃度與活力及死亡率之有中等程度的相關(P<0.05)，相關係數分別為0.54及-0.53。而BPSE稀釋的精子並未能看到HSP70濃度與活力之相關，可能是由於BPSE對精子之儲存保謢效果較佳所致。把精子樣本根據活力分群， 在PBS稀釋之精子中，活力較高(2和1.5)精子樣本之HSP70濃度顯著高於活力較低(0.01和0)的精子樣本(P<0.05)。置於41℃的精子之活力與死亡率均變差，但以PBS稀釋之HSP70濃度明顯地降低而以BPSE稀釋者則否。此結果顯示HSP70的減少與活力或死亡率之變差並沒有直接的關係。

Taiwan, located in the subtropical region, has high temperature and humidity in the summer. The heat stress reduces animals' reproduction performance. In vivo and in vitro studies have shown that various stressors transiently increase production of Heat stress proteins (HSPs) as protection against harmful in insult. This study attempted to know how the environment temperature affect cockerels' sperm quality traits and the 70kDa Heat stress protein (HSP70). In experiment 1, cockerels were randomly divided into two groups. The control group were housed in a 25℃ room and the treated group were housed in a room simulating hot and humid summer environment in Taiwan (37℃; R.H. 80%; from 1000 to 1400). The 12-week experiment period were parted intoadaptation (2 weeks), heat-stressed (6 weeks) and refractory (4 weeks) stages. Rectum temperature, semen quality and concentration of sperm HSP70 of cockerels were measured at every week. In experiment 2, cockerels semen diluted by Phosphate Buffered Saline(PBS) or Beltsville Poultry Semen Extender(BPSE) were set at 4℃, 25℃, 35℃ and 41℃ constant temperature water bath. Then semen quality and sperm HSP70 conc. were measured at 2, 4, 6 and 8 hours. In experiment 1, cockerel produced good semen volume and concentration during the 12 weeks experimental period, and the heat treatment made the semen volume of heat stress group higher than that of the control. During the heat stress and the refractory stages, sperm concentration and motility were lower and HSP70 concentration was higher than those in the adaptation stage. During the heat stressed stage, there was positive correlation between rectal temperature and blood pH value (0.29 and0.27 within the control and the treated groups, resp.) (P<0.05). Within the treated group, during the heat stressd stage, rectal temperature and blood pH value were found to be positively correlated with semen volume (0.21 and 0.31, resp.)(P<0.05), and negatively correlated with motility (-0.27and -0.23, resp) (P<0.05). These imply that if the chicken's rectal temperature and blood pH value raised due to unable to adapt the heat stress, he might increase water intake and consequently increase semen volume, but this high body temperature might also some influence on the sperm's motility. In experiment 2, when set at higher temperature (35 or 41℃), the sperm's motility and mortality significantly deteriorated with time, especially those diluted with PBS. Setting at 41℃ had more abnormal sperm, and most abnormal sperm at 41℃ for 8 hours were swollen. These may be effect of osmotic pressure and temperature. Observation of the variation of sperm HSP70 conc during the 8 hour setting period revealed that, those of the sperm diluted by PBS and set at 25℃ and those diluted by BPSE and set at any temperature were rather stable. The HSP70 concentration of those sperm diluted by PBS and set at 35℃ or 41℃ were decreased rapidly. Among PBS diluted sperm samples, sperm HSP70 concentration were correlated with motility and mortality (correlations were 0.54 and —0.53, resp). BPSE seems to have a better pretection effect, so that no relationship was found between HSP70 concentration and motility among those sperm samples diluted by BPSE. When sperm samples were grouped according to their motility, in the PBS diluted sperm samples, high motility score (2 and 1.5) group had higher sperm HSP70 conc than those of the low motility score (0.01 and 0) group. Any sperm set at 41℃ would have deteriorated motility and mortality, sperm HSP70 concentration of those diluted by PBS was also significantly decreased, however no significant variation was found in those diluted by BPSE. These results suggest that the decrease of HSP70 concentration in sperm was not directly related with the deteriorate of neither motility nor mortality.